Whitepaper - Ethereum Classic With Cover

Ethereum Classic Documentation, Release 0.1
dimension and represents the entire history of states at the discrete time points designated by the blocks on the
chain.
All Ether balances and values are denominated in units of wei: 1 Ether is 1e18 wei.
Note: “Contracts” in Ethereum should not be seen as something that should be “fulfilled” or “complied with”;
rather, they are more like “autonomous agents” that live inside of the Ethereum execution environment, always
executing a specific piece of code when “poked” by a message or transaction, and having direct control over their
own ether balance and their own key/value store to store their permanent state.
What is a transaction?
The term “transaction” is used in Ethereum to refer to the signed data package that stores a message to be sent
from an externally owned account to another account on the blockchain.
Transactions contain:
• the recipient of the message,
• a signature identifying the sender and proving their intention to send the message via the blockchain
to the recipient,
• VALUE field - The amount of wei to transfer from the sender to the recipient,
• an optional data field, which can contain the message sent to a contract,
• a STARTGAS value, representing the maximum number of computational steps the transaction execution
is allowed to take,
• a GASPRICE value, representing the fee the sender is willing to pay for gas. One unit of gas corresponds
to the execution of one atomic instruction, i.e., a computational step.
What is a message?
Contracts have the ability to send “messages” to other contracts. Messages are virtual objects that are never
serialized and exist only in the Ethereum execution environment. They can be conceived of as function calls.
A message contains:
• the sender of the message (implicit).
• the recipient of the message
• VALUE field - The amount of wei to transfer alongside the message to the contract address,
• an optional data field, that is the actual input data to the contract
• a STARTGAS value, which limits the maximum amount of gas the code execution triggered by the
message can incur.
Essentially, a message is like a transaction, except it is produced by a contract and not an external actor. A
message is produced when a contract currently executing code executes the CALL or DELEGATECALL opcodes,
which produces and executes a message. Like a transaction, a message leads to the recipient account running its
code. Thus, contracts can have relationships with other contracts in exactly the same way that external actors can.
What is gas?
Ethereum implements an execution environment on the blockchain called the Ethereum Virtual Machine (EVM).
Every node participating in the network runs the EVM as part of the block verification protocol. They go through
the transactions listed in the block they are verifying and run the code as triggered by the transaction within the
EVM. Each and every full node in the network does the same calculations and stores the same values. Clearly
Ethereum is not about optimising efficiency of computation. Its parallel processing is redundantly parallel. This
74 Chapter 1. Contents